In catabolic states of negative nitrogen balance and inadequate calorie intake, usually due to the inability to eat enough or to a disrupted gastrointestinal tract, intravenous total parenteral nutrition (TPN) using a central venous catheter can be lifesaving. Ordinarily, a subclavian or jugular catheter site is used. At present, these solutions contain a mixture of amino acids as a protein source and carbohydrates for calories. Fat emulsions provide more calories (9 calories per gram versus 4 for carbohydrates or protein) and lessen the problems of hyperglycemia. In general, the TPN solutions contain 20 to 25 percent carbohydrate as glucose plus 50 g of protein source per liter. To this are added the usual electrolytes plus calcium, magnesium, phosphates, trace elements, and multiple vitamins, especially vitamins C and K. Such a solution offers 1,000 calories per liter and the usual adult receives 3 L per day. This provides 3,000 calories, 150 g of protein, and a mild surplus of water for urinary, insensible, and other water losses. Any component of the TPN solution can be given in insufficient or excessive quantities, thus requiring careful monitoring. This should include daily weights, intake and output balances, urinalysis for sugar spillage, serum electrolytes, blood sugar and phosphate, hematocrit, and liver function tests with prothrombin levels in specific instances. Other than catheter-related problems, major complications include hyperglycemia with glucosuria (solute diuresis) and hyperglycemic nonketotic acidosis from overly rapid infusion. Reactive hypoglycemia or hypophosphatemia (refeeding syndrome) may occur after sudden discontinuance of the infusion (catheter accident). Another major complication involves infection, and strict precautions are needed in preparing the solutions and handling the infusion bottles, lines, and catheters. The catheter and its entrance site should be carefully covered with a topical antiseptic and a sterile dressing that is aseptically changed every 2 to 3 days. The infusion lines should contain a microporous filter, and all should be changed daily. Fungemia or gram-negative septicemia should be guarded against, and the catheter system should not be violated for drawing blood samples or for infusion of other solutions. Sepsis does not contraindicate the use of intravenous nutrition, but chronic septicemia without obvious etiology is the indication for removal and culturing of these catheters.